refactor(core): MP-25 Move User and AuthToken to core-domain

frontend/core/domain/src/commonMain/kotlin/at/mocode/frontend/core/domain/models/AuthToken.kt

@@ -0,0 +1,10 @@
+package at.mocode.frontend.core.domain.models
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class AuthToken(
+  val accessToken: String,
+  val tokenType: String = "Bearer",
+  val expiresAtEpochMillis: Long? = null
+)

frontend/core/domain/src/commonMain/kotlin/at/mocode/frontend/core/domain/models/User.kt

@@ -0,0 +1,11 @@
+package at.mocode.frontend.core.domain.models
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class User(
+  val id: String,
+  val username: String,
+  val displayName: String? = null,
+  val roles: List<String> = emptyList()
+)